Spotlight

Lucy Fortson is an experimental high-energy astrophysicist working on blazars, which means that she uses telescopes to try to understand how the highest energy gamma rays are being produced by celestial objects.

Fortson says that until ten years ago there were only a handful of known sources producing such high-energy gamma rays. With VERITAS (Very Energetic Radiation Imaging Telescope Array System), astrophysicists have identified over 40 objects emitting this type of radiation, such as supernova remnants, pulsars, starburst galaxies and active galactic nuclei. They have dubbed this last class of objects “blazars,” which are defined by an active galaxy with large jets of matter beamed from the center of the galaxy towards Earth. According to Fortson, the process which creates this type of radiation is ubiquitous but not yet understood. By investigating the properties of the host galaxies of blazars along with properties of their jets, she is looking at the problem from a different angle.

The first step for Fortson and her group is compiling a collection of blazars from all the different wavelengths, radio to gamma ray, in which they could be detected. This is done by utilizing many databases including the Sloan Digital Sky Survey which has images of a million galaxies – the trick is figuring out how to select the small fraction that are actually blazars. The next step is to look for trends in the information such as whether certain types of blazars have more massive black holes in the centers of their host galaxies, how the gamma rays are related to the power in the jets or whether blazars only exist in galaxies that are massive, red ellipticals and not smaller blue spirals. In this way, Fortson can begin to understand how blazars evolved over time and which galaxies should be targeted for deeper gamma ray observations in the next generation gamma-ray experiments.

One unique method that Fortson uses to obtain blazar host galaxy information is through her involvement in the Zooniverse collaboration. Zooniverse projects use the wisdom of the crowds to sort astronomical data. By using the internet to tap into the brain-power of hundreds of thousands of volunteers, parameters such as galaxy shape or bulge size can be determined more readily than with computers. With digital telescopes, terabytes of data can be taken in a relatively short amount of time. Computer algorithms can sort that data but Fortson warns that the algorithms are only as good as their proxies. For example, color is often used as a proxy for galaxy shape – spirals tend to be blue because of their heightened star formation while ellipticals tend to be red as their star formation phase has finished. Certain types of data such as color are relatively easy to program, but shapes are not. The human eye is still the best for sorting shapes and with these new big projects, astronomers have found that it is best to have lots of pairs of eyes on the case.

The collaboration began when 150,000 volunteers turned up online to help astronomers sort shapes of the one million Sloan galaxies. With such an unexpected response the Galaxy Zoo project (as it was then called) became a tool for all kinds of citizen science projects, such as Ancient Lives which uses the same type of shape recognition internet interface to try to decipher a massive collection of ancient Egyptian Papyri. Zooniverse also helps scientists develop more efficient algorithms as the humans provide millions of examples of what you want or don’t want and these examples are used to train the algorithms. And the Zooniverse is also sharing tools from one branch of science with another. For example, a handwriting transcription tool used for weather data collected in World War I by the British Navy has been adapted as part of the Ancient Lives project. All these analysis tools aim to turn “clicks” - data points given by the public - into scientific publications.

Lucy Fortson is an Associate Professor in the School of Physics and Astronomy, the Principal Investigator of the VERITAS grant and is on the Executive Team for Zooniverse, holding several grants that support the Zooniverse and research with Zooniverse data.